Lipodystrophy is a very dreadful disease and has become a major global health problem. It is a disorder of fat metabolism which causes lipohypertrophy, Lipoatrophy and Metabolic abnormalities. Moreover, lipohypertrophy includes the enlargement of dorsocervical fat pad (commonly called “buffalo hump”), expansion of the circumference of the neck by 5-10 cm, hypertrophy occurring in breast, central truncal adiposity resulting from abdominal visceral fat accumulation, symmetric and asymmetric lipomatoses. A rare pattern of lipoaccumulation involves formation of band like lipomatosis tissue symmetrically from the breasts, laterally to the axillae, Suprapubic fat pads (pubic lipomas) and the development of multiple angiolipomas.
Lipoatrophy includes a temporal wasting and loss of subcutaneous fat from the cheeks (buccal fat pad) which produces an emaciated appearance with prominent nasolabial creases. Further subcutaneous tissue is depleted from the arms, shoulders, thighs, and buttocks (peripheral wasting), with prominence of the superficial veins in these sites.
Metabolic abnormalities include augmentation in cholesterol and triglyceride levels and reduced high-density lipoprotein (HDL) cholesterol levels, Insulin resistance, type 2 diabetes mellitus, and lactic academia.
Lipodystrophy is very commonly associated with the HIV patients who are being treated anti-retroviral medicines. Such medicines can include HIV-1 protease inhibitors (PIs), Nucleoside reverse transcriptase inhibitors (NRTIs), Non-nucleoside Reverse Transcriptase Inhibitors (NNRTIs), Fusion Inhibitors, Entry Inhibitors—CCR5 co-receptor antagonist, HIV integrase strand transfer inhibitors etc. These medicines improve the survival of the patient but also produce lipohypertrophy, Lipoatrophy and other Metabolic abnormalities.
HIV-1 protease inhibitors (PIs) appear to be the strongest link to lipodystrophy in HIV-infected patients LDHIV as it inhibits maturation of sterol response element binding proteins (SREBP), which affect intracellular fatty acid and glucose metabolism and adipocyte differentiation (Mallon et al, J Infect Dis, 2005). Furthermore, the PIs also down-regulate peroxisome proliferator-activated receptor gamma (PPAR γ), an important nuclear transcription factor that is affected by SREBPs and is necessary for adipocyte differentiation and function and fatty acid metabolism.
Other factors, such as duration of HIV infection, age, and gender, may also contribute to the risk of development of LDHIV. The molecular basis of LDHIV is still remains unknown and no specific therapy is available for LDHIV.
Reverse transcriptase inhibitors (nRTIs) like stavudine, didanosine and zidovudine may cause mitochondrial toxicity by inhibiting mitochondrial DNA polymerase-γ in fat and other tissues and thus interfering with respiratory chain complexes. The result is impaired fatty acid oxidation and intracellular accumulation of triglycerides and lactate
In addition, lipodystrophy is also observed in acute HIV infection, lending support to a direct viral role as well. Potential host risk factors include age, sex, and race or ethnicity. Lipodystrophy is more common in older patients; fat accumulation is more common in women and lipoatrophy in men; and non-Hispanic black patients appear to be at lower risk of lipoatrophy. A genetic component is indicated by a recent analysis in AIDS Clinical Trials Group (ACTG), study 5005s, suggesting either predisposition or protection associated with mitochondrial DNA polymorphisms. Hulgan et al, J Infect Dis, 2008 describes that patients homozygous for C/C at the HFE187 locus (n=71) had a 0.6-kg and 12.5% loss of limb fat at weeks 48 to 64, with 37 (52%) of the 71 patients diagnosed with clinical lipoatrophy. By comparison, heterozygous patients with HFE187C/G had a 0.2-kg and 6.1% increase in limb fat, with 6 (26%) of 23 patients having clinical lipoatrophy (P<0.05 for all comparisons).
A number of strategies for reducing central obesity have been investigated such as stopping PI treatment but it is not effective. Changes in diet and exercise have produced improvements, but adherence to a regimen of lifestyle change is difficult for most patients. Liposuction may be applied particularly with dorsocervical fat accumulation, i.e., “buffalo hump”.
It is evident from the several studies that thiazolidinediones show no change in VAT (Pathogenesis and treatment of lipodystrophy, vol. 16, issue 4, October/November, 2004)
Testosterone replacement to physiologic levels reduces visceral adipose tissue (VAT), total fat, and abdominal fat and improves insulin sensitivity and lipid profile in older, non-HIV-infected men with upper body obesity and low testosterone levels. In a recent study, 88 HIV-infected men with central obesity (waist circumference>100 cm) and low testosterone levels (<400 ng/dL) underwent randomization to testosterone as a transdermal gel at a dose of 10 g daily or placebo for 24 weeks (Bhasin et al, J Clin Endocrinol Metab, 2007). The testosterone group had statistically significant reductions in abdominal fat (−1.5% vs +4.3%), abdominal subcutaneous adipose tissue (SAT) (−7.2% vs +8.1%), trunk fat (−9.9% vs +4.6%), and limb fat (−10.1% vs +3.1%); the latter finding is of potential concern in a population predisposed to lipoatrophy. No statistically significant difference in change in VAT (+0.9% vs +2.3%) was observed, and no statistically significant differences were observed in changes in lipid levels, fasting blood glucose levels, insulin levels, or insulin resistance.
Like testosterone, growth hormone (GH) has fat-oxidizing and lipolytic properties. A substantial proportion of HIV patients with central obesity (approximately 30%-40%) have impaired GH biology, including reduced GH mass secretion, reduced response to GH releasing hormone (GHRH) and free fatty acids, and increased somatostatin tone, which suppresses GH. A number of recent studies have assessed GH treatment in HIV patients with fat accumulation. In 1 study, 325 HIV patients with increased waist: hip ratios and increased VAT measurements received.
Although, the growth hormone (GH) and GH releasing hormone (GHRH) therapies show some promising result as they have fat-oxidizing and lipolytic properties however, there are limitations to their use. They are parenteral therapies and either expensive (rhGH) or not FDA-approved (tesamorelin). Thus far, there is evidence of waning durability of the reduction in VAT after their discontinuation, short-term increases in insulin resistance with rhGH, and small short-term reductions.
Recent research publications have shown the use of two lipid-lowering classes of drugs, statins and fibrates, antiretroviral switching strategies and use of insulin-sensitising drugs as having some beneficial effect on lipodystrophy. However, no single therapy is able to reach desirable clinical end point for HIV associated lipodystrophy.
Hence it is desirable to develop a compound which can overcome the above discussed drawback associated with prior art and develop a therapy for HIV associated lipodystrophy.
Hypolipidemic agents which are PPAR modulators have been disclosed in WO 91/19702, WO 94/01420, WO 94/13650. WO 95/03038, WO 95/17394, WO 96/04260, WO 96/04261, WO 96/33998, WO 97/25042, WO 97/36579, WO 98/28534, WO 99/08501, WO 99/16758, WO 99/19313, WO99/20614, WO 00/23417, WO 00/23445, WO 00/23451, WO 01/53257.
WO 03009841 discloses compounds of the following general formula

These compounds are reported to be hypolipidaemic agents. This document also discloses sodium and calcium salts of some of the compounds disclosed therein. However, the sodium salts of the compounds of the present invention was difficult to isolate due to rapid degradation while the Calcium salt was poorly absorbed limiting its efficacy and possibility of further development. Further, the calcium salt was also found to degrade on long term storage. It has surprisingly now been found that certain compounds and their selected salts are effective in the treatment of lipohypertrophy, lipoatrophy and metabolic abnormalities in HIV patients.